A conventional variable resistance device is disclosed in Japanese Utility Model Laid-Open No. Hei 1-95602. This laid-open application describes a sensor for detecting the opening of a throttle valve. A portion of the sensor is shown in FIG. 4. In the sensor, the connection between a throttle valve opening detecting portion provided on a substrate 3 supported by a substrate support 8 and a contact terminal 31 formed together with a housing 1 is achieved by a terminal portion 26 and a tongue piece conductor 36. The terminal portion 26 is electrically connected to the throttle valve opening detecting portion, and the tongue piece conductor 36 has a springy elasticity that presses in a direction substantially perpendicular to a surface of the terminal portion 26 so as to electrically connect the terminal portion 26 to the contact terminal 31 thus enabling electrical connection of the terminal portion 26 to an external device. The housing 1 is connected with a cover 9 at a mount portion 1a provided in the housing 1.
However, since the electrical connection of the terminal portion 26 on the substrate 3 to the contact terminal 31 is made by pressing the tongue piece conductor 36 against the terminal portion 26 in this conventional variable resistance device, there exists the possibility that an insulating layer will be formed in the contact junction between the tongue piece conductor 36 and the terminal portion 26 by oxidation or moisture, thereby causing problems with electrical conduction. In addition, a contact failure may be caused between the substrate 3 and the contact terminal 31 by vibrations or the like. Thus, the conventional device is considered inadequate in that it fails to ensure good electric conduction between the contact terminal 31 and the throttle valve opening detecting portion. If the terminal portion 26 and the contact terminal 31 are soldered to each other in an attempt to achieve reliable conduction, the production man hours will increase. Further, a space will be required between the substrate 3 and the housing 1 in order to fix the substrate 3 to the housing 1, thereby resulting in a construction that contradicts the size reduction demands associated with variable resistance devices.